The present invention relates to integrated circuits having multiple power supplies that operate in multiple power modes and, more particularly, to a built-in self test (BIST) circuit that tests the status of the power supplies in the multiple power modes.
Systems on a Chip (SOC) usually have multiple on-chip power supplies that operate in multiple power modes such as sleep, deep sleep, and functional mode. It is a complex task to test a SOC having a sophisticated power supply system with multiple power modes to verify the power supply system. In a typical design process, power supply connections are confirmed by a back-end team using CPF (Common Power Format). Thus, issues concerning power supply connections are found quite late in the design flow. Further, power supply connections may not even be verified for each of the different power modes. For example, a connection of a power supply to a circuit module may be checked but not necessarily checked to ensure the proper voltage is being supplied to the circuit module in each of its various power modes.
It also is important to check the status of the multiple power supplies, in the multiple power modes, during both manufacturing and operation. Therefore, there is a need for a technique for testing power supply status in multiple power modes during IC design, manufacturing test, and device operation.